Interpretation difficulty of normal versus abnormal radiographs using a pediatric example

Background: Radiograph teaching files are usually dominated by abnormal cases, implying that normal radiographs are easier to interpret. Our main objective was to compare the interpretation difficulty of normal versus abnormal radiographs of a set of common pediatric radiographs.Methods: We developed a 234-item digital case bank of pediatric ankle radiographs, recruited a convenience sample of participants, and presented the cases to each participant who then classified the cases as normal or abnormal. We determined and contrasted the interpretation difficulty of the normal and abnormal x-rays items using Rasch Measurement Theory. We also identified case features that were associated with item difficulty.Results: 139 participants (86 medical students, 7 residents, 29 fellows, 5 emergency physicians, and 3 radiologists) rated a minimum of 50 cases each, which resulted in 16,535 total ratings. Abnormal cases were more difficult (+0.99 logits) than were normal ones (-0.58 logits), difference 1.57 logits (95% CI 1.2, 2.0), but there was considerable overlap in difficulty scores. Patient variables associated with a more difficult normal radiograph included younger patient age (β = -0.16, 95% CI -0.22, -0.10), history of distal fibular tenderness (β = 0.55, 95% CI 0.17, 0.93), and presence of a secondary ossification centre (β = 0.84, 95% CI 0.27, 1.41).Conclusions: While abnormal images were more difficult to interpret, normal images did show a range of interpretation difficulties. Including a significant proportion of normal cases may be of benefit to learners

OR13-1 Burosumab Improves the Biochemical, Skeletal, and Clinical Symptoms of Tumor-Induced Osteomalacia Syndrome

Tumor-induced Osteomalacia (TIO) and Epidermal Nevus Syndrome with osteomalacia (ENS) are rare conditions in which ectopic production of FGF23 by tumor (TIO) and bone (ENS) lead to renal phosphate wasting, impaired 1,25(OH)2D synthesis, osteomalacia, fractures, weakness, fatigue and decreased mobility. In an ongoing open-label Phase 2 study (NCT02304367), 17 adults were enrolled and treated with burosumab, a fully human monoclonal antibody against FGF23. Key endpoints were change in serum phosphorus and osteomalacia as assessed from trans-iliac crest bone biopsies. The per protocol (PP) analysis included 14/17 subjects who received 0.3-2.0 mg/kg burosumab every 4 weeks (W). Three subjects were excluded: 1 received subthreshold dosing (0.3 mg/kg at Day 0 and 0.15 mg/kg at W8, W32, and W72); 2 were diagnosed with X-linked hypophosphatemia post-enrollment. Ten subjects in the PP group had paired bone biopsies at baseline and W48. Mean ± SE histomorphometric values for the 8/10 subjects with osteomalacia at baseline were 20.4 ± 4.2 µm for osteoid thickness (OT), 23.0 ± 7.2% for osteoid volume/bone volume (OV/BV), and 66.1 ± 10.6% for osteoid surface/bone surface (OS/BS); baseline median (Q1, Q3) for mineralization lag time (MLT) was 1672 (1102, 2929) days. At W48, histomorphometric indices improved as shown by mean percentage changes in OT (37%), OV/BV (40%), OS/BS (-5%), and MLT (median percentage change -78%). Serum phosphorus, fatigue, and physical functioning are reported for the PP group. Mean (SD) serum phosphorus was 1.5 (0.3) mg/dL at baseline and 2.6 (0.8) mg/dL when averaged across the mid-point of the dose interval through W24. After W24, serum phosphorus, assessed only at the end of the dose interval, maintained this increase through W72. Mean (SD) Global Fatigue Score decreased from 5.3 (2.8) at baseline to 3.6 (2.9) at W48 (p=0.020) and to 3.3 (2.7) at W72 (p=0.004). The SF-36 mean (SD) physical component summary score increased from 34 (11) at baseline to 39 (10) at W48 (p=0.059) and to 42 (10) at W72 (p=0.003). Mean (SD) vitality score increased from 41 (14) to 47 (12) at W48 (p=0.075) and to 49 (12) at W72 (p=0.012). The mean (SD) number of sit-to-stand repetitions increased from 6.9 (4.0) at baseline to 8.6 (4.2) at W48 (n=10; p=0.004). By W72, all 17 subjects had ≥1 adverse event (AE). There were 13 serious AEs in 6 subjects, none were considered drug-related. Tumor progression occurred only in subjects with a history of tumor progression prior to enrollment. One subject discontinued treatment prior to W48 to treat tumor progression with chemotherapy. There was 1 death, considered unrelated to treatment. In adults with TIO Syndrome, burosumab was associated with improvements in serum phosphorus, osteomalacia, mobility, quality of life, and reductions in fatigue

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements